Method of making a ai-si-mn-li anode for high temperature galvanic cell



Feb., EL M967 BW. KING, JR.. ETAL TEMPERATURE GALVANIC CELL original Filed sept. 25, 1964' METHOD OF MAKING A Al-SL -MN-LL ANODE FOR HIGH w Q MHZ@ VZ United States Patent O 3,305,357 METHOD F MAKING A Al-Si-Mn-Li ANQDE FOR HIGH TEMPERATURE GALVANIC CELL Burnham W. King, Jr., 4545 Coach Road, Columbus, Ohio 43221; Thomas G. Byrer, 784 Olde Settler Road, Columbus, Ohio 43214; and Walter A. Hedden, 145 E. South St., Worthington, Ohio 43085 Original application Sept. 25, 1964, Ser. No. 399,414. Divided and this application Apr. 15, 1966, Ser. No. 543,779

2 Claims. (Cl. 75--135) This invention relates to a high temperature galvanic cell `anode and to the method by which it is made, and is a divisional application of application Serial No. 399,414, led in the United States Patent Office on September 25, 1964.

The object of the present invention is a provision of a new and improved galvanic cell that operates successfully at temperatures in the order of 650 C. to 700 C., which on the Fahrenheit scale are 1202 to 1292 F. respectively.

In general, "a high temperature galvanic cell or battery consists of solid metal electrodes and a ceramic as an electrolyte. An iron-enamel-silver Austin cell consists of a silver cathode separated from an 'iron `anode by a glass electrolyte. In this type of galvanic cell, oxides in the glass appear to function as the current carrying electrolyte, with electrical power produced -by the oxidation of the iron anode and with the voltage depending greatly on the particular metallic composition of t-he anode.

For high electrical output from the galvanic cell, it is desirable that the cell anode should be of a high melting point metal composition and of a high free energy of oxidation. The metals in the anode must have melting points that are suliciently high to avoid slumping `at the temperature at which a desired electrolyte is applied to the anode. This characteristic was confirmed experimentally by the preparation of several metal anode compositions. The performance of one of the compositions as an anode in a high temperature galvanic cell, was evaluated as illustrated in the accompanying drawing.

In the accompanying drawing:

FIG. 1 presents experimental results derived from an anode of the composition in melt number 6 described hereinafter at 650 C., compared with comparable results from an Austin cell at 650 C.; and

FIG. 2 presents corresponding results at 700 C.

Each of the anode compositions that were prepared possesses a significant content of metals that impart a high free energy of oxidation to the anode alloy of aluminum, silicon, manganese and lithium metals.

The following table presents prepared heats of Al-Si- Mn-Li metal compositions with melting points above 1400 F., which corresponds to 760 C.

*Plus an additional parts of Li to make up for losses during degassing.

All of the heats were prepared in a clay graphite crucible.

The heats numbered 4 and 5 were prepared by melting the charged aluminum, adding the silicon at 871 C. or

1600 F. and stirring the melt. The manganese was added at 1038 C. or 1900 F. as the stirring of the melt was continued and the temperature was increased as the lithium was added. The melt was poured into a mold that formed the anodes. The melting points of the anode from heat number 4 was about 1580 F. or 860 C. The composition of the anode from heat number 5 slumped at 1475 F. or 802 C.

The heats numbered 6 and 7 were prepared by melting the aluminum at 660 C. or 1220 F. The temperature was increased and when it reached 871 C. or 1600 F. the silicon was added and the melt was stirred. At the temperature 1038 C. or 1900 F. the manganese was added with continued stirring. At the temperature 1038 C., the melt was fluxed for 6 minutes using chlorine gas, and the lithium was added. The fluxing with chlorine gas was continued after the lithium was added, and then the `melt was skimmed and poured into the mold producing the anode.

The heat number 8 was prepared by first melting the aluminum at 660 C. The silicon was added to the molten aluminum at 927 C. or 1700 F., with stirring. The manganese was added at 1038 C., with stirring, and with iluxing for 6 minutes, using chlorine gas. The temperature was maintained at l038 C. while the lithium was added with stirring. The melt was then skimmed and was poured into the mold to form the anode.

Example 1 The anode metal composition of heat number 6, coated with a selected enamel electrolyte and tired in a nitrogen-rich atmosphere, may be taken as a successfully operating embodiment of the present invention. Silver was applied to a 2.1 square inch area of the enameled surface, to complete the galvanic cell submitted to test.

The galvanic cell so made was heated to 4650 C. and, on open circuit a potential of 2.62 volts was measured, as indicated at the time zero along the ordinate of FIG. l of the accompanying drawing.

This cell had a high power output at 650 C. of about 150 mw. per square inch for the first minute. The initial power output decreased from the 134 mw. per square inch to about 50 mw. per square inch after 20 minutes of operation. The power output was measured using a resistance load of 19 ohms, which is equivalent to a load of 10 ohms on a 4 square inch area.

For a comparison with this experimentally confirmed performance of the anode that is desclosed herein, the typical power curve for the iron-enamel-silver cell is shown near the bottom of the graph in FIG. l of the accompanying drawing.

The cell was operated at 650 C. for 80 minutes, after which the load was disconnected and the temperature of the cell was increased to 700 C.

The same resistance load was again applied and the power output was measured for a period of minutes.

The results obtained at both 650 C. and at 700 C., in comparable juxtaposition are shown in FIGS. 1 and 2 of the accompanying drawing.

It is to `be understood that the composition of the anode and its method of manufacture, that are disclosed herein [as a separate article as well as a part of its cell, are submitted as `being illustrative embodiments of the present invention and that equivalent modiiications may ybe made therein without departing from the spirit and the scope of the present invention.

We claim:

1. The method of making a high temperature galvanic cell anode by melting aluminum Iat about 660 C., increasing the temperature of the melt to about 870 C. and stirring silicon into the melt, increasing the temperature to about 1038 C. and stirring manganese into the melt, adding lithium to the melt with stirring, and pouring the melt.

2. 'Ihe method of making a high temperature ,galvanic cell anode by melting by weight about 74 parts of aluminum at about 660 C. temperature, increasing the ternperature at about 871 C. adding to the melt about 3 parts of silicon by weight and stirring the melt, increasing the temperature and at about 1038 C. adding to the melt about 20 parts of manganese by weight and stirring 10 the melt, iluxing the melt for about 6 minutes using chlorine gas, adding to the melt about 3 parts of lithium by Weight, and stirring as the uxing with chlorine gas is continued, and pouring the melt into a mold shaping the anode.

References Cited by the Examiner UNITED STATES PATENTS 1,595,218 8/1926 Paez 75-148 2,219,095 10/1940 Schuttler 75--138 3,081,534 3/1963 Bredzs 75-148 3,157,494 ll/1964 Larson 75--148 DAVID L. RECK, Primary Examiner.

R. O. DEAN, Assistant Examiner. 

1. THE METHOD OF MAKING A HIGH TEMPERATURE GALVANIC CELL ANODE BY MELTING ALUMNUM AT ABOUT 660%C., INCREASING THE TEMPERATURE OF THE MELT TO ABOUT 870%C. AND STIRRING SILICON INTO THE MELT, INCREASING THE TEMPERATURE TO ABOUT 1038%C. AND STIRRING MANGANESE INTO THE MELT, ADDING LITHIUM TO THE MELT WITH STIRRING, AND POUR ING THE MELT. 